[olug] device identifiers in kernel error messages

[Nick Walter]

I spent a few minutes perusing the kernel source and here's what I noticed.
The "I/O Error:" line from the scsi module
(/usr/src/linux/drivers/scsi/scsi_lib.c) is using kdevname() to print out
hexadecimal device numbers and the EXT2-fs message from the EXT2 module
seems to be using decimal.  hex 11 = decimal 17 so the two error message are
both whining about device major 8 minor 17, which is indeed /dev/sdb1.

Note: I did this quickie research against the stock 2.4.2-2smp kernel that
comes with Red Hat 7.1.  I can't verify it's correctness in regards to any
other setup, but it does seem to make sense.

Ain't it great to have the source code for your O/S? :)

Nick Walter


-----Original Message-----
From: mmartin at mitec.net [mailto:mmartin at mitec.net]On Behalf Of Mark
Martin
Sent: Monday, November 05, 2001 3:43 PM
To: Omaha Linux Users Group
Subject: [olug] device identifiers in kernel error messages


I was wondering if someone out there might be able and willing to help
me with a question regarding how the kernel names devices in messages
that it logs through syslog.  I've been receiving I/O errors and I'm
trying to identify the source of the errors.  Specifically, I am
receiving many errors such as

Nov  4 04:02:20 ergo kernel:  I/O error: dev 08:11, sector 25165872
Nov  4 04:02:20 ergo kernel: EXT2-fs error (device sd(8,17)):
ext2_read_inode: unable to read inode block - inode=1569795,
block=3145734

Am I correct in thinking that 08:11 in the first message refers to the
device with major number 8 and minor number 11?  Similarly, does the
device name in the second message sd(8,17) refer to major number 8 and
minor number 17?  Major number 8, refering to a SCSI hard drive, makes
sense in both cases and minor number 17, narrowing it down to /dev/sdb1,
makes sense in the second case.  But minor number 11, which refers to
/dev/sda11, doesn't make any sense for my system because the only
partitions on sda are partitions 1, 2, and 3.

I would very much appreciate help with interpreting these messages.  If
one of the error messages does not refer to major and minor numbers, a
reference where I could read about the naming convention used would also
be appreciated.  I looked through the kernel sources and documentation
and a little in LDP but maybe I didn't know where to look.

Many thanks,

Mark

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